用 ast 重写代码;Python [英] rewriting code with ast; python
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问题描述
我正在学习 AST,它似乎是一个强大的东西,但我很困惑代码去了哪里以及为什么它消失了.说我要重写
I am learning AST and it seems like a powerful thing but I'm confused where the code went and why it disappeared. Say I want to rewrite
example = """def fake(x):
y = ['useless list']
return x
"""
作为
example = """def fake(x):
return x
"""
我看不到任何以这种方式重写的方法.我什至找不到获取行文本的方法:
I can't see any way to rewrite in this manner. I can't even find a way to get the text of the line:
In [1]: example = """def fake(x):
...: y = ['useless list']
...: return x
...: """
In [3]: import ast
In [4]: p = ast.parse(example)
In [5]: p
Out[5]: <_ast.Module at 0x7f22f7274a10>
In [6]: p.body
Out[6]: [<_ast.FunctionDef at 0x7f22f7274a50>]
In [7]: p.body
Out[7]: [<_ast.FunctionDef at 0x7f22f7274a50>]
In [8]: f = p.body[0]
In [9]: f
Out[9]: <_ast.FunctionDef at 0x7f22f7274a50>
In [10]: f.body
Out[10]: [<_ast.Assign at 0x7f22f7274b10>, <_ast.Return at 0x7f22f7274c10>]
In [11]: f.name
Out[11]: 'fake'
In [12]: newf = f.body[1:]
In [13]: newf
Out[13]: [<_ast.Return at 0x7f22f7274c10>]
In [14]: z = newf[0]
In [15]: z.value
Out[15]: <_ast.Name at 0x7f22f7274c50>
In [16]: z.value.id
Out[16]: 'x'
更令人惊讶的是它如何为您提供开头的线条,而不是结尾的线条.所以你知道一个函数从哪里开始,但不知道它在哪里结束,这是没有用的
Even more surprising is how it gives you the lineno of the start, but not the end. So you know where a function begins, but not where it ends, which is of no use
如何在没有列表 y
的情况下获取代码并重写此函数?谢谢
How can I grab the code and rewrite this func without the list y
? Thank you
推荐答案
也许这对你有帮助:
import ast
import astor
example = """
def fake(x):
y = ['useless list']
return x
"""
tree = ast.parse(example)
# iterating through list which is represents function on ast
for ind, item in enumerate(tree.body[0].body):
if isinstance(item, ast.Assign) and isinstance(item.value, ast.List):
del tree.body[0].body[ind]
break
print astor.to_source(tree)
更好地使用更多 OOP:
Better using more OOP:
class RemoveList(ast.NodeTransformer):
def visit_FunctionDef(self, node):
self.generic_visit(node)
for leaf in node.body:
if isinstance(leaf, ast.Assign) and isinstance(leaf.value, ast.List):
del node.body[node.body.index(leaf)]
ast.fix_missing_locations(node)
return node
tree_class = ast.parse(example)
remove_list = RemoveList().visit(tree_class)
print astor.to_source(tree_class)
from redbaron import RedBaron
example = """
def fake(x):
y = ['useless list']
return x
"""
red = RedBaron(example)
methods = red.find_all('DefNode').data
for data in methods:
if len(data.value.data) > 0:
for vals in data.value.data:
if vals[0].type == 'assignment' and vals[0].value.type == 'list':
index = vals[0].index_on_parent
par = vals[0].parent
del par[index]
break
print red.dumps()
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